Electronic systems and equipment such as computer systems, network interfaces, storage systems, and telecommunications equipment are commonly enclosed within a cabinet or housing for support, physical security, and efficient usage of space. Electronic equipment contained within the enclosure generates a significant amount of heat. Thermal damage may occur to the electronic equipment unless the heat is removed.
Low-profile computer system installations present significant thermal management difficulties. For example, Electronics Industry Association (EIA) standard racks are commonly used to house electronic equipment. In relatively large systems, for example 2U or larger where “U” is the measuring unit for racks and rack-mountable components with 1U=1.75″ or 44.45 mm, most cooling air enters through the front of the enclosure and exits through the rear. For low-profile systems, the enclosure front is significantly blocked by hard drives and media devices. The rear is blocked by power supplies and input/output (I/O) connectors. To lower air flow resistance through the enclosure and enhance cooling, typical 1U and 2U servers use a perforation on the top of the enclosure to supply cooling air and to vent heated exhaust. In a rack fully loaded with standard electronic equipment 1U and 2U devices, such as servers, computers, I/O equipment, and the like, a small clearance is interposed between adjacent stacked devices. For example, in some systems approximately 0.050 inches of clearance separates the devices. The small space between systems permits fresh air from the room to enter near the front of the enclosure and warmed air to exhaust near the rear through separate perforation patterns in the enclosure. However, an unimpeded and direct airflow path exists between the enclosure inlet and exit allowing hot exhaust air to re-circulate from the devices to the inlet vent, a problem that is exacerbated by cable blockage of airflow exiting the rear of the enclosure. Re-circulation of heated air can create thermal difficulties that may result in system overheating and failure.
Re-circulation of heated air can impact performance of electronic equipment. If airflow patterns allow re-usage of air that is previously heated by electronic equipment, attempts to cool electronic equipment can fail and less effective heat transfer from the equipment to the cooling airflow can result. In some circumstances insufficient heat transfer can take place and the equipment may overheat and potentially sustain thermal damage.